Electrode Placement and Montages Flashcards

Which montage type is most useful for localizing the PHASE REVERSAL of an epileptiform discharge?

Answer: Bipolar montage

Bipolar montages are best for localizing epileptiform discharges because phase reversals occur at the electrode directly over the focus.

In the revised IFCN electrode nomenclature, electrode T5 is now called:

Answer: P7

In the revised nomenclature, T5 was renamed P7 because it overlies the posterior temporal/parietal region, not the mid-temporal region.

A technologist notices a phase reversal at F7 in a bipolar montage. What does this indicate?

Answer: Maximum electrical activity at F7

In a bipolar montage, phase reversal at a specific electrode indicates that the maximum (or focus of) electrical activity is located at that electrode.

How many electrodes are used in the standard 10-20 system?

Answer: 21

The standard 10-20 system uses 21 electrodes, including 19 scalp electrodes plus A1 and A2 ear reference electrodes.

Which electrode site is used as the nasion landmark in the 10-20 measurement system?

Answer: The bridge of the nose between the eyes

The nasion is the depression at the bridge of the nose between the eyes and serves as the anterior skull landmark for 10-20 measurements.

In a circumferential (transverse) bipolar montage, electrodes are chained:

Answer: Around the head from left to right across the coronal plane

A transverse (circumferential) bipolar montage chains electrodes in a left-to-right order across the coronal plane, running from one side of the head to the other.

What is the primary advantage of using an average reference montage?

Answer: It reduces bias from any single reference electrode location

The average reference montage uses the average of all electrodes as the reference, which reduces the distortion that can occur when a single reference electrode is near active brain tissue.